An energy drink is to be tested on motorists as part of a study into the problem of drivers who doze off at the wheel.

It is estimated that a quarter of all road deaths in Scotland are caused by driver sleepiness, and scientists hope studying the effects of energy drinks will help them reduce that toll.

According to government statistics there were 4,000 serious accidents and almost 400 deaths on Scotland's roads in 1998.

Scientists at Loughborough University's Sleep Laboratory say driver sleepiness is acknowledged to have been a major cause, claiming more lives than alcohol.

Red Bull contains high levels of caffeine

Now they are launching a study which they hope will help stem the growing tide of fall-asleep crashes.

They are appealing for volunteers from high risk groups such as doctors, journalists and night shift workers to take part in interactive tests using car simulators.

Participants will be examined for the way they respond to energy drinks like Red Bull which contain high levels of caffeine.

Police chiefs and automobile groups have expressed support for the research.

A Royal Automobile Club spokesman said drowsiness on the roads is a major transport issue and anything which could help combat it should be welcomed.

The Automobile Association recommends that drivers should never attempt to drive more than two hours without taking a break of at least 20 minutes, and should never drive more than eight hours in one day.